Old Testament

Classified as "The Law", the first 5 books of the bible were written by Moses.
It is not until halfway through Exodus in chapter 20 where we see the LORD dispense the law! By comparison, the entire book of Genesis has no mention of the law. Instead, God's focus in this book of beginnings is to demonstrate mankind's utter failure and disobedience through multiple dispensings of God's instructions commencing at the Garden of Eden.
Leviticus 26 is where Israel yokes themselves to a perfromance based rightness with God rather than trusting in His Jehovah-ness!

Joshua

2 Kings

Judges

These books of the bible are often referred to as "The Historical Books of The Bible" but they also are a grim reminder of Israel's inability to accept The LORD God as their righteousness. After the death of Moses, Joshua lead the Nation of Israel. A true warrior and man of God, his leadership was only a minor bright spot in the sordid history of this disobedient nation as noted in the book of Judges; reference 21:25 "In those days there was no king in Israel: every man did that which was right in his own eyes."

The Poetical Five

Job's - his affliction, patience, pondernace, prayer, perseverence culminating with God's 60 questions demonstrating His power
Psalms - 150 spiritual songs, prayers, poems and prophecies of Christ; specifically during His passion
Proverbs - Trust in the LORD with all thine heart and lean not on thine own understanding.
Ecclesiastes - Solomon's look-back on the vanity of life
Song of Solomon - The love story of a man and a woman symbolizing God's love for us

Although classified as "new testament" letters, these books were gospel accounts of the earthly ministry of Jesus Christ.
During His earthly ministry and kingdom offer to Israel, the dispensing of The Law was still in operation; these letters could easily be classified under the old testament (ref. Mattew 5:17, Hebrews 9:15-18)

Prophets can be considered foretellers of faith as they received direction from God. Prophets declared the truth about God—by being foretellers—predicting what God will do. Prediction is not seen as an occasional or an unimportant activity in the Old Testament. It is the way the prophet went about his work. These books are referred to as "major" and "minor" prophets by no means implying more or less importance in communicating God's revelation to Israel.